Tape guides are used in a magnetic recording tape cassette for guiding a magnetic recording tape along a predetermined path in the cassette. As a magnetic recording tape is guided across the surface of a tape guide, any irregularities in tape tracking will adversely effect recording and reproducing of magnetically recorded signals. Thus, the quality of magnetically recorded signals depends upon precise, accurate tracking of the tape across a tape guide. Tracking is particularly troublesome for tapes having relatively rough back-coats. Many varieties of tape guides are known in the art.
Metal tape guides comprising a cylindrical sleeve having a slit in the axial direction are disclosed in Umehara U.S. Pat. No. 4,429,823 and Shiba U.S. Pat. No. 4,168,043. A polymeric guide in which the polymer is an acetal copolymer is disclosed in Tollefson U.S. Pat. No. 4,745,508. Carbon fiber filled acetal tape guides are disclosed in the Japanese publication JP60-28063.
Tape guides whose surfaces are relatively rough-textured are disclosed in Umehara U.S. Patent No. 4,429,823, Schoettle U.S. Pat. No. 4,276,575, Smetana U.S. Pat. No. 4,390,119, and Oishi U.S. Pat. No. 4,427,166. Tape guides with concave guiding surfaces are disclosed in Nelson U.S. Pat. No. 3,889,900.
Tape guides are mounted over a tape guide post in an assembled cassette. Typically, tape cassettes, including the tape guide posts, are made from polymeric resins. In the case of metal tape guides, the sharp edge on such guides skives off plastic shavings from the tape guide post as the guide is slid over the post for mounting. This debris can collect on the tape and cause dropouts during recording or playback. Metal tape guides, and particularly stainless steel tape guides, are also much more expensive than polymeric tape guides. As for polymeric tape guides, there continues to be a need for more durable polymeric tape guides that exhibit excellent tracking and tape guiding characteristics.